This may be simple or trivial, but when writing in the past tense, is it wrong to switch to present tense to use the verb "may be"?

Sharon may be irrational, but it was not completely her fault.

Sharon may have been irrational, but it was not completely her fault.

The first sentence implies that Sharon often acts irrational, and this is something that can be taken for granted. The second sentence does not imply this; it tells the reader that Sharon was acting irrational at a certain point in time, but she is not always like that.

I know it can be jarring to shift tenses in writing, especially in the middle of a sentence. However, I cannot tell whether or not the first sentence with "may be" is disconcerting to read. Depending on the situation, I would use either sentence, but I want to know how the first flows and whether or not it is grammatically incorrect.

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    This does not answer the question exactly, but if I am parsing the question correctly, you want to indicate that she is habitually irrational while excusing her for some of the fault during this one instance. Is that right? If that is the case, I think it would be better written as: "Sharon may have acted irrationally, but it was not entirely her fault this time." This time implies there are other times she acts irrationally, since it suggests you feel the need to specify an exemption for a particular instance of irrationality, which would be unnecessary if there event was a singularity.
    – Tonepoet
    Jul 26, 2016 at 7:44
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    It's not jarring to shift tenses unless you did it without any reason. (Like I just did.) Both sentences are fine. Jul 26, 2016 at 15:37
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    @Tonepoet I did not make it clear in the question, but the second sentence is closer to my intended meaning. I like the sentence you came up with; in a way, it combines the irrationality of Sharon's character from the first sentence with the time specification in the second.
    – Symantra
    Jul 26, 2016 at 17:41

2 Answers 2


Sharon may be irrational, but it was not completely her fault.

This states that currently it is possible that Sharon is irrational.

Sharon may have been irrational, but it was not completely her fault.

This states that recently and up to but not including the present, it was possible that Sharon was irrational.

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    I don't believe "but it was" says anything about whether Sharon is irrational at present; it just says that she was irrational at the time referenced in the past. Oct 17, 2022 at 21:17

In your case, mixing present and past tense is acceptable.

You are conjoining two seperate sentences together. It is possible for the left-hand sentence to be written in a different tense from the right-hand sentence.

Sharon may be irrational, but it was not completely her fault.

Sharon may be irrational. However, it was not completely her fault.

For the specific example, you provided, we can replace the word but with the string . However,

The word but behaves in English like the word and behaves in mathematical logic.

The word "and" is like a plus sign (+) in mathematics. For example, when mathematicians write 1+2, 1 and 2 are considered to be two seperate things.

Likewise, you have two sentences, written in two different tenses. You have conjoined the two seperate sentences together.

Given any two grammatcially sentences [X] and [Y] the string [X] and [Y] is also a grammatically-correct, fully-formed, sentence. Sentences [X] and [Y] are not required to be in the same tense (past, present, future).

Words such as "and" and "but" are somtimes used to concatenate two seperate sentences together.

I say "somtimes," rather than" always," because it depends on whether the word "but" or "and" are used at a high level or low level.

A word is used at a "high level" if that word apoears close to the root node when representing an English sentence in a tree diagram.

The word "and" is used at its highest level when it would be acceptable to replace the word and with . (a period followed by a space).

Consider the following strings. Example 2 is inrentionally grammatically incorrect.

  • The house was large and old. (Ex 1)

  • The house was large . old. (Ex 2)

  • The house was large and the house was old. (Ex 3)

  • "The house was large. The house was old." (Ex 4)

Like mathematics, the English language has a distributive property.

2*(4+9) = (2*4) + (2*9)

In the sentence the house was large and old the string The house was is distributed across the phrase large and old.

Somtimes the word "and" is deeply nested inside of an English sentence. This is analogous to how a plus sign can be deeply nested inside of a mathematical formula. Other times, the word "and" is used at a high level (it is used close to the root of the sentence).

When the word "and" is used at a high level, it has a special property. When "and" is replaceable by period-space, then the operand sentences are allowed to be in two different tenses.

Sharon may have been irrational, but (logical-and) it was not completely her fault.

Sharon may have been irrational. It was not completely her fault.

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